The influence of aeroponics on the adaptation of Mentha piperita L. and Melissa officinalis L. microclones and accumulation of phenolic compounds

Relevance. One of the time-consuming stages on which the success of clonal micropropagation depends is the transfer of microclones from in vitro conditions to ex vitro conditions. At this stage, plants experience stress, which leads to their death. In addition, the low survival rate of plants to ex vitro conditions is primarily due to their poorly developed root system, non-functional stomatal apparatus, poorly formed cuticle, as well as the use of non-sterile soil. The effectiveness of clonal micropropagation depends on the choice of the nutrient substrate and the technology of adaptation of microclones to ex vitro conditions. Hydroponic and aeroponic technologies are designed to increase the productivity and economic efficiency of clonal micro-propagation of plants, by reducing the time of cultivation of cloned plants.

Purpose of the study. The aim of the study was to study the effect of aeroponics on the growth and accumulation of phenolic compounds in the microclones of medicinal plants Mentha piperita L. and Melissa officinalis L.

Material and methods. The object of the study was the microclones Mentha piperita L. and Melissa officinalis L., which were originally propagated on a hormone-free nutrient medium containing mineral salts according to Murashige and Skооg (MS). Microclones were adapted to ex vitro conditions in two ways: on an aeroponic installation and directly in the soil. Adaptation was carried out on two groups of plants: 1 – with roots, 2 – without roots (the root system was removed with a scalpel before planting on an aeroponic installation or in the soil). The results were taken into account at the end of the adaptation cycle, while taking into account the length of the root system (cm) and the height of plants (cm). Based on the results obtained, the growth index (I) and the specific growth rate (µ) were calculated, and the total content of phenolic compounds and flavonoids was determined.

Results. It is established that at the last stage of clonal micropropagation, it is advisable to use aeroponic installations that allow rooting and adaptation of microclones simultaneously. The developed method makes it possible to obtain high-quality planting material, since this reduces the percentage of plant death, increases the growth and development of green biomass, as well as the root system. The rooting of micro-shoots during adaptation is achieved by including in the composition of the nutrient solution of IBА at a concentration of 0.5 mg / l. In addition, under these conditions, there is a change in phenolic metabolism, which manifests itself in an increase in the total content of phenolic compounds in microclones.